1. Field
The presently disclosed subject matter relates to a multi-input optical switch. More particularly, the presently disclosed subject matter relates to a multi-input optical switch that can include an optical system which detects a tilted direction, a rotational angle, and up/down of an operation lever by means of light as a detection medium.
2. Description of the Related Art
There has conventionally been proposed a multi-input switch as shown in FIG. 17, which has multiple operation means. In FIG. 17, the multi-input switch 50 includes an operation lever 51, a first switch unit 52 which detects whether the operation lever 51 is depressed or not (by a depressing operation applied to the operation lever 51), a second switch unit 53 which detects a tilted direction (caused by a tilting operation applied to the operation lever 51), and a third switch unit 54 which detects a rotational angle (caused by a rotating operation applied to the operation lever 51). The first switch unit 52, the second switch unit 53, and the third switch unit 54 are respectively provided with a push-button switch 55, potentiometers 56, and a photo coupler 57.
The first switch unit 52 detects whether the depressing operation is carried out (or not) as follows. When a knob 58 attached to one end of the operation lever 51 is pressed down, an action rod 59 attached to the other end of the operation lever 51 moves down, and turns on the push button switch 55. When the pressing force is removed, an energizing force provided by a coil spring 60 returns the operation lever 51 to its original state, the action rod 59 moves up, and the push button switch 55 is turned off.
The second switch unit 53 detects the direction of the tilt as follows. A pair of approximately semicircular movable arms 62 respectively including a slot 61 are arranged orthogonally with respect to each other. A pair of shaft portions 63 are provided on both ends of the respective movable arms 62, one of the shaft portions 63 being fixed to a rotational shaft 64 of the potentiometer 56, and the operation lever 51 passing through an intersection of the slots 61. When the knob 58 is tilted to a desired direction, the rotational shafts 64 of the potentiometers 56 are rotated via the shaft portions 63 provided on the movable arms 62, and the tilted direction of the operation lever 51 is thus detected. When a tilting force is removed, the energizing force of the coil spring 60 returns the operation lever 51 to its original state, and the rotational shafts 64 of the potentiometers 56 return to the neutral position of the rotation via the shaft portions 63 of the movable arms 62, thereby returning the potentiometers 56 to the neutral state.
The third switch unit 54 detects the rotational angle as follows. Light reflecting bodies 65 are formed on an outer periphery of the action rod 59 provided on the end portion of the operation lever 51. When the knob 58 is rotated, light emitted from a light emitting portion 66 of the photo coupler 57 and that is reflected by the light reflecting body 65 on the action rod 59 is received by a light receiving portion 67 of the photo coupler 57. The received photo signal is output to a rotational angle detector 68, and the rotational angle detector 68 thus detects the rotational angle of the operation lever 51 (refer to the conventional art Japanese Laid-Open Utility Model Publication No. H5-55433, for example).
The multi-input switch 50 configured as described above has mechanical contacts within the components, which causes problems in durability and detection reliability for a long-term operation.
In order to detect the tilted direction by a tilting operation applied to the operation lever 51, it is necessary to provide the potentiometers 56 with an external component and circuit which apply signal conversion, such as voltage conversion and A/D conversion, to an output therefrom, resulting in a complicated overall configuration, and an increased cost.
With regards to the detection of the rotational angle that changes due to the rotating operation applied to the operation lever 51, though a relative rotational angle can be detected, an absolute rotational angle with respect to a reference position cannot be detected.
Similarly, if the operation lever 51 is rotated at a high speed, a detection miss may occur, resulting in a possible degradation of detection precision.